Al Qaeda's new deputy leader, Atiyah Abd al-Rahman, was killed on Aug. 22 in Pakistan's tribal areas by a CIA drone strike, according to an official who was briefed on the intelligence report, a major setback to an organization still reeling from Osama bin Laden's death.

Al-Rahman, a Libyan, was al Qaeda's "operational leader," planning attacks, helping manage the terrorist group on a daily basis and communicating with and speaking on behalf of both bin Laden and his successor, Ayman al-Zawahiri, according to U.S. officials.

His death is "a tremendous loss for al Qaeda, because Zawahiri was relying heavily on him to help guide and run the organization, especially since Bin Laden's death," a senior administration official said.

"The trove of materials from bin Laden's compound showed clearly that Atiyah was deeply involved in directing al Qaeda's operations even before the raid," the official said. "He had multiple responsibilities in the organization and will be very difficult to replace."

Al-Rahman was killed Monday in North Waziristan, but his death was not confirmed until last night, according to the official who was briefed on the intelligence.

Al-Rahman was on a list of five militants that Secretary of State Hillary Clinton handed over to Pakistani officials three weeks after bin Laden was killed.

At the time, a senior U.S. official and a senior Pakistani official said the United States requested help hunting al-Rahman down and killing him.

Today, a senior Pakistani military official said Pakistan's intelligence services did not provide any intelligence for the Aug. 22 drone strike that U.S. officials say killed him.

Other than Zawahiri himself, al-Rahman was the most senior al Qaeda member on the list of five militants that Clinton landed over. The United States saw the days after bin Laden's death as a chance to deliver a death blow to al Qaeda, especially while the group chose its next leaders.

Last month, while flying to Afghanistan, Defense Secretary Leon Panetta said the U.S. was "within reach of strategically defeating al Qaeda."

"We've now identified some of the key leadership within al Qaeda, both in Pakistan as well as in Yemen and other areas, that if we can be successful in going after them, I think we can really undermine their ability to be able to do any kind of planning to conduct any kind of attack on this country," Panetta said.

U.S. officials said the files discovered in bin Laden's Abbottabad, Pakistan home made clear that al-Rahman was in regular communication with bin Laden, discussing plots and personnel. The files, the U.S officials say, also gave "critical" clues about al-Rahman's location.

"His combination of background, experience, and abilities are unique in al Qaeda," another U.S. official said. "Zawahiri needed Atiyah's experience and connections to help manage al Qaeda. Now it will be even harder for him to consolidate control."

Al-Rahman has been a high value target for years. Even al Qaeda knew how important he was to the CIA.

When Humam al-Balawi, a Jordanian who pretended to infiltrate al Qaeda but turned out to be a double agent, wanted to convince his handlers that he had access to al Qaeda's senior leaders, he provided a short video of himself sitting next to al-Rahman, according to The Triple Agent, a book about Bilawi by Washington Post reporter Joby Warrick.

On the day of the drone attack, a Pakistani official told ABC News that two missiles had struck a car in Norak Village, North Waziristan and killed three militants. There was no information on the target.

Al-Rahman joined al Qaeda as a teenager and helped a group led by bin Laden fight the Soviet Union in Afghanistan.